import {
  CDATA_SECTION_NODE,
  COMMENT_NODE,
  DOCUMENT_NODE,
  DOCUMENT_FRAGMENT_NODE,
  TEXT_NODE,
  NODE_END
} from './constants.js';

import {START, NEXT, PREV} from './symbols.js';
import {getEnd} from './utils.js';

export const isConnected = ({ownerDocument, parentNode}) => {
  while (parentNode) {
    if (parentNode === ownerDocument)
      return true;
    parentNode = parentNode.parentNode || parentNode.host;
  }
  return false;
};

export const parentElement = ({parentNode}) => {
  if (parentNode) {
    switch (parentNode.nodeType) {
      case DOCUMENT_NODE:
      case DOCUMENT_FRAGMENT_NODE:
        return null;
    }
  }
  return parentNode;
};

export const previousSibling = ({[PREV]: prev}) => {
  switch (prev ? prev.nodeType : 0) {
    case NODE_END:
      return prev[START];
    case TEXT_NODE:
    case COMMENT_NODE:
    case CDATA_SECTION_NODE:
      return prev;
  }
  return null;
};

export const nextSibling = node => {
  const next = getEnd(node)[NEXT];
  return next && (next.nodeType === NODE_END ? null : next);
};